#include <iostream>
#include <algorithm>
#include <cstdio>
#define N 1100
using namespace std;
int main()
{
    int t,i,n,a[N];
    cin>>t;
    while(t--)
    {
        cin>>n;
        for(i=0;i<n;i++)
            scanf("%d",&a[i]);
        if(n==1)
            cout<<a[0]<<endl;
        else
            cout<<0<<endl;
    }
    return 0;
}